Telephone system



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/N VEN To@ R. E HE RSE V ATTORNEY SePt- 11, 1945- R.'E.-AHESEY 2,384,620

TELEPHONE SYSTEM Filed Nov. 9, 1944 9 Sheets-sheet 2 SWITCH 0 l SEC.

/NVENTOR R. E. HERSEV T TORNF V Sept 11, 1945 w R. E. HERsEY 2,384,620

TELEPHONE SYSTEM Filed Nov. ,9, 1944 9 sheets-sheet s MARKE/e ccr No 2,31 4

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TELEPHONE SYSTEM Filed Nov. 9, 1944 9 Sheets-Sheet 4 TIM/NG C672 /A/l/E/v To@ R. E. HERSEV Br;

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ATTORNEY Sept- 11, 1945. R. E. HERSEY 2,384,620.

- TELEPHONE S-YS TEM Filed Nov. 9, 1944 9 Sheets-Sheet 5 TIN/N6 CCT.

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Sept. 1l, 1945. v R. E. Hl-:RsEY 2,384,620

TELEPHONE SYSTEM Filed Nov. 9, 1944 9 Sheets-Sheet SWITCH l S SEC.

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LINK I6 ATTORNEY SPt ll, 1945. l R. E. HERsEY y v 2,384,620

TELEPHONE SYSTEM Filed Nov. 9, 1944 9 Sheets-Sheet 7 FROM MARI( J /N VE N TOR R. E. HERSEV BK' A 7' rom/EV Sept- 11, 1945. R. E. HERSEY 2,384,620

TELEPHONE SYSTEM 'Filed Nov. 9, 1944 -9 Sheets-Sheet 8 TIM/NG CC 7:

DIAL TONE LINK /I SWITCH 4 /NVE/vroR Rf HE RSE Y @g4/nwe ATTORNEY Sept. ll, 1945. R.'E. HERsEY 2,384,620

TELEPHONE SYSTEM Filed Nov. 9, 1944 9 Sheets- Sheet 9 L//vk la slr/rch 4 I WEA/TOR REHERSEV 5y:

Patented Sept. 11, 1945 UNITED STATES? PATENT oF-FICE 2,384,620

TELEPHONE SXSTEJW'` Ralph E. Hersey, Madison, N: 1;, assigner to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation ofi NewIlfor-k4 Application November 9, 1944, Serial No. 562,599f

5 Claims. (Cl. IVW-22)- This invention relatesto telephone s-ystemsand-l particularly to systems in which cross bar switches are employed to automatically extend.v connections between subscribers? lines.

An object is to simplify andimprove'the op.

erating. characteristicsv of systems of thiskind` andto increase the number of 1 sinriultaneous4 subscribers connections thaty may be. maintainedthrough such switches without materially increasey ing the' commoncontrol circuit equipment for. the establishing of such connections.

Heretofore cross-bar switcheshave been used'.

in small capacity systems for` establishing connections betweenvsubscribers over interconnect ing links.A In such prionsystems the subscribers lines were multipled toa nuniberloffswitches or sections of switches providedwith itsown links and in whichJ an idle link in any switch was-used toV connect a calling subscribers line with a called subscriber-s line in the `switch in which the link-` usel appears. In some systems connectionsbetween subscriberslines overl interconnecting links were controlledby the aid of control lrelay groupsorV marker circuitsand' minor step-by-stepf switches which selected and operatedthe-usual individualselect and hold-magnets of` the' crossbar switches.

The present invention relates to small capacity systems. of these general types and an inventive feature thereof relates tothe grouping ofl the subscribers lines in the switches and Athe arranges. ment of the-links and the' control marker circuitsA and minor switches. If thesefeaturesc arci applied inone hundred line capactysystems. the` arrangement would consist of ve crossA bar.

switches with all subscribers lines, multipledtov all live switches and with two Vso-called home links individual to each switch, each link including, minor switches for the-selectionf-,of. the Icalled line in the corresponding switch. VThe linesy would be divided into vegroups or sections in each switch; and an individual markedcircuit provided for each section but witheach marker; circuit more or less associated witha particular pair of .home links ,andthecorresponding switch. With this arrangement when a subscriber in such a group calls the associatedmarker circuitvcontrolsthe associated :cross bar switch .to establish;

a connection between this calling` lineandtheY outgoing branchI o-f a first idle-.one Aof said home links, thenwhen the callingl subscriber dialsv a desired subscribers-numberthe minor switchesy associated with this linkoperateto-actuate this associated switch to connect lthe incomingbranch live secLiQnsas. follows:. Inthe first horizontal.

is'the, connections will beA established throughA a@ -rst idlel homedink in a firstsucceeding switch inwhich anidlellink mayrbefound;

Referring` to the drawings, Fig. le showsE the. general. plan of five switches and@ ve: pairs ofv homelinks ina oneihundredline systemiembody ing-theV applicants invention;

Figs: 2 to 9farrangedin accordancev with Eig.V 10k show this system insufficient; detailfor;Y thel establishing of, a Vconnection betweenacalling;l srJibscribezfs.V line1 and a` calledv subscribersline bythe-aid ofz the: associated Imarker circuits and home links. l

If, reference-is,notl made 'particuli-arly, to -Eig 1f and partly., to, Figs, 2and 6,4 itl should bernoted that the veswitches: are numbered switch n-to switch 4.,respectively.,and thatA the switches, are each dividedfnto ve sections.- The subscribersare,grollpcdstoi appear and be multipled. in the. same manner, in allofthe switchesand in the;

levelr subscribers r`-llll and lll appear each at. four vertical.. positionsinthe rst section No. 0 and,

subscribers,` |124 and 03,appeara four, vertical posit tions yinthe secondsectionNo. I, etc.unti1.ithe subscribers' numbers llmandllappear in the section.No.,. 4`A Similarly,subscribers` Nos.y I0' to. I9; appear` in', V the samemanner inthe second4 horizontal level.; while similarly succeednglsubscribers `groups,citen appear in the succeeding eight horizontal'levels making ,a total of 100 subscriberslines appearing` each four times in the l same positionsinah ve switches. With reference to the home-li,nks, two-links appear for connection to allithe verticalsr in each switch, fory example,` links!! andflappear as the homelinks imswitchiO-in allfive sections andas the 4lines inY each-sectionappear four'times and eachl linkh-asanoutgoinggbranclr and an incoming vbranch in-each-sectiorrf'our sets of `left and right relays are provided furthe-connection of each line to either link to feither l theoutgoingv or thel incoming' branchel If; for example,` thev available connections for the subscribers over the four verticals in section to the links 0 and I are considered, the rst vertical is connectable through the first left or right relay to the outgoing branch of link 0; the second vertical through the second left or right relay to the incoming branch of link 0; the third vertical through the third left or right relay to the outgoing branch ofl link I and the fourth vertical through the fourthrleft or right relay to the incoming branch of link I.

Similarly the other four groups of four vertcals* each in the other four sections I to 4 of switch IlY are connectable through the same four groupsV or left or right relay to links 0 and I in the same manner. The arrangementrisf such that these two home links 0 and I are home links for lines 00 to I9 in this switch No. Il and similarly the succeeding four pair of links vare home links re-A spectively, for the succeeding four groups o f n In general, to establish a connection from a` calling subscribers line -to a called subscribers linefwhen the calling l'subscriber lifts his receiver, the associated marker circuitis controlled to operate the selectmagnetfor the levelin which the calling subscribers line is located in theswitch where the associatedhomelinkis located and also the associated left or right relay and the holdl magnet in -the section `where theV calling line is located in said sfwitch'for connecting the callingsubscribers line to the outgoing branch of the rst idle link of the two home links.l l The subscriber then, after receiving his dial tone, dialsl the chosen subscribers number andthe minor switches in the chosen link operate the -select ma-gnet representing the Vlevel -in .'which the-called subscribers line is locatedfasf'wellras the as-l sociated left or rightrrelay and the associated hold "magnet inthe section in this switch `where' the called line is locatedrto` connect'thecalled line tothe'incoming branch of the chosen link. The kcalled subscriber is then" rung from' the chosen link and when'the `called subscriber answers the connection is completed between ,the subscribers through this 'link'.- If ,the` homelinks are busy certain special relays are operated to connect the, calling subscriber bythe aid of the associated marker circuit'to the next switch in which an idle link is available and the called subscriber is then connected by 'the minor switches in the chosen link and by the aid of Vthe marker circuit associated with the chosen home links 1 and 0, respectively,.f,or linesl 00y tokl9 in this switch, while FigsA 6150 Q'show the" switch No. 4 with the associated marker circuit and home links.

If then the subscriber No. 00 lifts his receiver his line relay 300 will operate from battery and ground through the winding of this relay over the calling subscribers loop and contacts of the associated cut-olf relay 30|. Relay `300 closes the circuit for the relay P0 from battery, contactsvof the GTI) and PI relays, winding of this P0 relay, contacts of relay T0 to ground at con- Y tacts of relay 300. Relay P0 closes an obvious circuit for the operation of relay TI). It should Ibe noted that in this marker circuit for switch No. 0 there would be two relays of the type T and two of the type P, that is, T0 and TI and P0 and PI, or a total of ten of these two types of relays for the five marker circuits. It should (be noted that ten subscribers lines have access to each of these two types of relays. The operation of the T0 relay marks the level in which the calling subscribers line is located, that is, the rst or lower -levels in these switches while TI marks the second level. It should now :be noted that on the operation of this relay T0, therefore, the select magnet 200 will .be operated from battery, winding of this magnet, contacts of the GTI) relay associated with this marker, contacts of relays T0 and 300 to ground. This select magnet, therefore, marks the level in which the calling line is located in switch 0 provided the two home links for switch 0 are idle as indicated iby the released condition of the GTI) relay. It should also be noted that one of the ten U relays in thismarker is now operated which in this case will indicate that the calling subscribers line is located in the first section of switch 0. In this case, therefore, U0 will operate from battery, winding of this relay, contacts of relays GTO, T0 and 300 to ground. There is also one relay LTD inY this marker circuit which is normally released if the home link No. 0 is idle so that now von the operation of relay U0 the left relay 20| for this iirst section of Yswitch 0 will operate from battery, winding of relay 20|, contacts of relays LTO and U0 to ground, indicating that the calling subscriber is located in the rst vertical of the first section of switch 0. The hold magnet for this first section Iwill also Aoperate from battery through the windingV of hold magnet 20f3,.contacts of relaysLTO `and U0 to ground. .The operation of the left relay 20| and thev hold magnet'203 after the operation of select magnet200 now, therefore, establishes a connection at thecross-point 204 between the callingsubscribers line V0I! and the outgoing branch of linkA 0 to the tip and ring leads through the windings of* relay 500 torbattery'and ground. The sleeve lead isalso connected'as noted rto contacts-of relay I in link 0. As the result of this connection relay 500 operates. Relay 500 in turn closes an obvious circuit for the operation of relay 50|. This relay in operating closesa circuit for the operation of cut-olf relay 30| of the subscriber 00 over the 'sleeve lead. Cut-off relay 30| releases relay 300, relays P0, T0 and U0 in the marker. circuit. vThis causes therelease of theselect magnet 200 in the switch No. 0, While the hold magnetand the left relay 20| are maintainedoperated over their own armatures and front contacts and the sleeve connection` to ground at relay50l. Dial tone is now transmitted from the dial tone source 503 ,over contact of relay SIIII,l condenser I506 and the tip lead tothe calling subscriber rNo. 00 indicating that the circuits areready for dialing.

#If now the subscribezvNo.v `ffdesires to establish a connectionI to .subscriber -No.` 80, he will dial the -first digit `8. 'I-heA first impulse. of this digit will release relay 50B-in the-'link 0,' yThis causes the operationptrelay 15|0from battery, windingofihis relay, contacts# of-relays 50|, and 500 tolgroundf. Relay |0op`erates relay 504 4from battery, winding of thisfrelayfcontacts ofrelays liII,` 5H) and 50Ito ground. lRelay `51Min operating 'removes the dialtonefrom the subscriber-s line Vvlielay-5lll also closes-va circuitfor the 0pera-tion otthe stepping magnet 5I2for theminor switch- 5I-3-to make this switch-take one step.v At the end Vof @this rst impulse relay 5001releases and the stepping magnet SI2 also releases.- Relays 504 andr 5I0remain operateddue to` their slow torelease-charaeteristic during the pulsing.- `On each succeeding impulse from the calling subscriber-s linel on the releaseof relay-500 the stepping magnet StZ-takes an. additional. step until eight steps have been taken when relay BUB-iinally remains operated This causes the release of relay -5I0 whichfnowcauses the operation offrelay 5I I Vdue to the removalA of'ground at the armature and back contact of` relay- 500. `This circuit for Arelay SIIVrnayY betraoed from battery, windings of relays 504 andv 5H, contacts of rrelays '5Mv and/SI5 to ground.v lThe select :magnetfm in switch 0 is nowoperatedfrom-battery winding of this magnet, 'the veighthV contact and the brush `of `switch 5I3 rto ground at `rcontacts of relay `54 I. indicateszthat-the called subscribers line is located in the eighth horizontal level. If now the calling subscriber dials the second-digit '1, that is 'to say,

one impulse only', the-release ctrelay 5110v in-respense to this digitcauses thereoperation of relay 510 which causes the operation of relay SI1 from battery, Winding .of'fthis relay, contacts of relays 5H, 510 and 504 to -ground--Relay '511 in operatingc'loses a locking' circuit for relays 50"! 1 and 5H at its lower armature and --ront contact to ground and contacts of relay '504.V AThe step ping magnet 520 for theswitch 52| is vncwr'also operated from battery, winding of- `this `nia-griet, contacts of relays f51II, Vitil and 500 to ground. The operation -of this *magnet causes Ythe brushes oi' 'switch '-521 to take `one step. At the end-"of impulsen/hen 'relay 500 again 'operates the circuit for the stepping Ania-guet v520 liis opened Aat the contacts -of V'relay 50B and releases. As no other succeeding impulses-are received, 'relayS-I 0 releases '-aridlcauses the operation of relay A-5 I-5 from lbatftery, winding of "this relay, contacts-oi relays SITI, 5IU-and`50^l I'to ground, Relay 515 in operating closes A"a locking circuitforitself through 'contactso relay 50d. As the result of--the switch 521 taking l'one step, the left -rclay'ZI'I) in the first sec'tion the switch 0 operates from batter-y, winding of 'this relay, the -irst contacts *of fthe switch'banik i152 2 Y overlthe Thrush-'thereof tofgrou'nd at contacts of relay SP5. lThis determines that the called line is located Aat the crossg-pcintfjzflg. in the first section of` switch 0 for thervegtial 'xlea'ding'ltothe linkli. vThe hold magnetfogtlis section for establishing a connection at point 2 I2 -is'now operated from battery, Winding of this hold magnet 2I5, the first contact of bank 523 and the brush thereof to ground at relay 5I5. rlhis establishes the connection at cross-point 2 I 2 between the called subscriber 80 over the associated verticals and through contacts of the left relay 2I0 to the incoming branch of link 0 and the sleeve connection to ground through relay 525 through the cross-point 2 I2, locks the hold magnet 2 I5 and the left relay 2I0, the same as the hold. magnet 2&3 andleft relay .20| werelocked'.. over the sleeve to. the outgoingz'end. .of thelink. 0, and causes the. operation `of-.thisrelay E25;` Relay 525,.in.operating, closes acircuitfor the operation of the relay 526 from battery;windingy of this relay, contacts of the ringing. relays 521 and525 to ground at .relay 530. yRelay 526 now a es` vinterr'nittent ringing..curre'nt. from I. the source 528fthrough the ringing .relay 521.. `This ringing source. does not` operate` relay 521- until the called subscriber removes hisreceiverf. The operation of relay 521 releases relay 526.and. causes the operation of the' line relayA 539.*` .ReF lay 53 |lcloses` an obvious holding circuit for `relay 50I-and the calling and 'called subscribers lines are now lconnected through condensers 508 and 53 lin the Vzero link ofswitch 0.- A' 'f When theY calling and called subscriber release the connection, relays SIJUand5to-arev released.` This causes the releaseof'relay SIU-which causes the-release voi`relays 504, 5H, 5I-1, 5I5and the release'of relayiII 'closes the circuitfor thereleasema'gnets '532 and -533 ofthev switches l'ZI and 5I3 tocause them to return to normaland the left relays 20| and 210 and the hold magnets 203 and 2I5 `are-released causing the release-of theconnectionthrough link 0 for the 'subscribers aswell as the re1ay--525and the circuits are new in'con'dition Afor the establishing Aof other calls.

`If link 0 lhadbeen busy when thesubscrlber 00 called, it should he noted-'that the relay `515 f in link Dwould have been operated. `The circuit for relay LTU would Athen extend `'from lbattery through vthe winding of this relay, contacts of Vrelaylf'andthe corresponding relay-Mfinv link No. l to-grourid; VRelay LTO `then locks tothis ground at relay EIB through its lower armature and-frontfcontact. Relay LTD transfers the leads in the marker circuitto-make a selection to-ccnn'ectthe callingsubscriber to link ANoll and `the selection ofthis' link` proceeds as inthe selection of link lexcept that in this casethev left relay 2I1vand the hold magnets 2I8 are operated to establis'hk the connection to link No. 1 "from the calling subscriber lat the cross-point220.

should both 'home links' for switch c Yse busy, the GTO relay in the marker circuitfor switch 0' would operateA from battery, winding of this relay,'contacts` o f relays 5`I5 and 4I5'to` ground. TherelayGTll in operating transfers leads from the T0 and TI relays through contacts oflthis relay GTU to corresponding Ufrelays of the marker for the second switchgan'd, if the links for` this secondv switch are idle, the secondswitchwould beactuatedto establish "the `connection from the calling subscriber through this switchto theiirst idle home link associated with this switch in the same manner as Athe connection was establishing through switch No.0. That is to say the marker circuit for swit'chr will employ the PiljtilV and GTI! relays but the U relays in thev marker for switch No.A vwill be employed for this connection. Should the jhorne 'linlsin thesecond switch No. I also be busy, the' corresponding GTL relayfor the marker for switch Nol I will be operated and the home links for the third switch No. 2 would be available for establishing the connections through switch No. 2. These GT relays will opcrate as soon as the home links are all busy and transfer to the home links of succeeding switches. Thus normally a first section of a switch Il would employ the home links Nos. 0 and I for establishing connections to the calling and the called subscribers and similarly the succeeding switches would employ their home links, but if the home links'i'n any switches; are. busy whenthe corre-l sponding subscribers yin.- the-correspondingl switch call, the iirst idle .home -link 'of ;a-succeeding switch would .be employedfor. establishing 'he'.

connection. l r. i .-1 f

What is claimed is:4

1. In a telephone system, la'plurality of-cross bar switches, links individual toiea'ch switchrekh link having'an outgoing andan incoming branch, groups of 4subscribers lines. multipled to `allthe switches, a markercircuitfor eachswitch, .each marker circuit arranged totv serve, an individual group. of lines when calling and being responsive to acall from any oneoisaid.- linesfor actuating the associated switch to connect the callingI line with the outgoing-branch ofan -idlelinkindi-l vidual to said switch and thereafter releasing ffor service with other lines, when calling, means-responsive to dial pulses received fromjsaidlcalling line for actuating said switch vto `connect ,any` called line in any group to the incoming .branchof said link, means thereafter responsive *inY said link for ringing the called linel'and forfrdisconnecting the ringing when the vcalled,subscriber answers. 'Y f r n;

2. In a telephone system, aplurality ot, crossl bar switches, links individual Yto eachswitch, each link having an outgoing and an incorningbranch, groups of subscribers lines multipledto all'lthe switches, a marker circuit for each..switch,ea ch marker circuit arranged to normally serve a pai'.- ticular group of lines when calling A.and beingref sponsive to a call from any one of'ssaidlines for actuating the associated switch ,toconnect the outgoing branch of an idle associatedlinktofsad calling line, means operative if all thelinksoia switch are busy and a call originates V.from the group of lines normally served bythe associa-ted marker circuit for changing 4.the functions of this marker circuit and the markencircuit of anadjacent switch so that said adjacent switchrisacY tuated to connect Ythe outgoing branch of anzidle link individual to. said adjacentfswitch tto'said calling line, and means responsive todial pulses received from the Acalling line foractuating this latter switch to connect any calledline tothe firi-v coming branch of saidlast-mentioned linkf.

3. In a telephone system, a plurality of. .cross barswitches, links individual to each switch, each link having an outgoingrand an incomingbranh; groups of subscribers lines multipledftoallfthe switches, a marker circuit-for 'eachfswitchg'eacli .marker circuit arranged to normallyfserveg'an in'-` idividual group of lines when`calling- 'and being responsive to calls from 'any one of,V said. linesfor actuating the -associated switch tolconnectzthe calling line to the outgoing branch of -an idle link individual to said Aswitchrneans operated-'ifallV links of a switch are -busy andal .'callorigiates from the group of lines normallyfservedby-the associated marker circuit for uuuzmg a parrfon of this marker circuit Vanda partof the-marker circuit of an adjacent switch ltoV a-ctuate saidfadjacent switch and connectthe callin'gline ltri-the outgoing branch of an idle link individualto said adjacent switch, means operative when the calling line is connected to said link forreleasing parts of the '.two marker circuits to normal cpndition, and means responsivefto dial pulses received from the lcalling line for actuating this iatterswitch to connect any'call'ed line to, the incoming branch of saidlink. Y j g l r 4. In a telephone system, a` plurality of cross bar switches, two links individual to eachswitch, each link having an outgoing branchand an incoming branch, groupsof subscriberslines-multipled to appear in all'switches, each-line appear-v ing in each switch at four cross-poinlSfone point serving to connect the line with `the outgoing branch of one link, a `second` pointserving tol connect the line with fthe outgoing branch'ofwthe second link, a thirdrpoint servingto ,connectthe line with thevincoming branchof the first link and .for-the fourth point serving to connect the line with the incoming branch of the second link,` a marker circuit for each switch', each marker circuit arranged tozserve an individual groupof lines when calling and responsive to a` call from any one of said lines for actuating the associated switch to connect the calling line with the outer going branch of a rst idlelink individual to said group and at the corresponding cross-point in said switch, means responsive-,to dial pulsesin. coming over said calling line over the'connected outgoing branch-of said link for actuating said switch to connect any calledline fromA any group to the incoming branch of said link'at the cor-f respondingcross-pointt, i f

5. In a telephone.system,a plurality-oi ;cross bar switches arrangedina certainl order, links individual to each switch, .each link having an outgoing and an incoming branch, groups of subscribers lines multipled to' all the switches; a marker vcircuit foreach switch, each marker cir-V cuit arranged to normally serve an individualgroup of lines when calling andbeing responsive to calls from any one of said 'lines for actuating the associated switch to connect the calling line to the outgoing branch of and idle link individual to 'said switch, vmeans, operative if `all links cfa switch are busy and a call'originates from. the group of lines normallyserved bythe 4associated marker circuit for utilizingv a part only of this marker circuit and a part ofj the markercircuit ofv another switch to connect the calling line to the outgoing branch of an idle individual. linkjin said other switch, this connectionbeing vestab, lished through the next succeeding of; the remaining switches arranged in said order in which an idle link is. available, means operative when the calling lineis' connected tosaidridle :link for releasing said par-ts ofthe two marker circuitsused to normal. conditionY and means responsive to dial pulses received from vthe calling line Afor actuating the switch used to connectY any called line-tothe incoming branch of said idle link.A 1 A RALPH E. 

